Possible Clues:

• Hollow rustling in strong wind that clears the old gorge?
• Wash out the mouth and throat
• Use Listerine, e.g.
• Lar gets an egg for his sore throat
• Wash out one's throat
• Use mouthwash audibly
• Swish with mouthwash
• Use Listerine, perhaps
• It may be a mouthful
• Wash your mouth out!